1. Field
Disclosed herein is a purification material in the form of a flat layer, that provides a high rate of water flow through the material, requires minimal head of water to effect a flow rate and purification rate acceptable to consumers, and provides good removal of contaminants from water, rendering it purified and potable.
2. Description of Related Art
Certain purification systems for drinking water that rely on a pressure head of the water above the purification material are known, such as the BRITA pitcher filtration systems and the like. These systems are typically used in households to remove the tastes and/or odors associated with chlorinated tap water. However, these systems generally provide a purification material having a relatively low rate of flow through the purification material. Partly this may be by design, because the purification material does not provide sufficiently fast purification kinetics, so that contaminants are only slowly removed from the water, requiring a longer residence time in the purification material. Another reason for the low flow rate is the structure of the purification material itself. Purification materials that are insufficiently porous or that have such high pressure drops across the material that only lower rates of flow-through are possible so that the system may retain water for periods of time in excess of that required for purification.
Moreover, the media used in existing filters causes problems at the beginning and end of the useful lifetimes of the system. At the beginning of use of a fresh purification material, carbon fines will be released into the water, often requiring 5-10 liters of flow through before this release ceases. In addition, some of the media used in these purification systems can swell over time, particularly as organic contaminants are sorbed from the water, which can slow the flow rate even more. For example, certain coconut shell carbons used as purification media can, over time, slow down their flow rates to 1000 cc over 30 minutes, a flow rate that is unacceptable to consumers. Depending upon the level of dissolved organic contaminants in the water, this swelling can drastically reduce the effective lifetime of the system.
Additionally, the form factor of these systems is generally in the form of a tube, sometimes of several inches in length. Because of this, the filters often extend for some distance into the reservoir of purified water that results from use of the purification system, which can result in contact between purified water and water that has not yet been purified.
Accordingly, there remains a need in the art for a purification material that is sufficiently porous and that has sufficiently low pressure drop across the purification material to allow for rapid flow-through of water being purified, thereby decreasing the pressure head necessary to use the system, that has sufficiently fast purification kinetics to adequately purify the water flowing through the material in the lower residence time that results from the rapid flow-through, that does not have prolonged release of carbon fines during initial periods of use, that does not restrict flow from swelling with organic contaminants, and that reduces the opportunity for purified water to come into contact with unpurified water.